Heating device



FIG. 1 is a perspective view of a heating device showing my new design;

FIG. 2 is a rear elevation view thereof;

FIG. 3 is a left elevation view thereof, the right elevation view beingidentical thereto;

FIG. 4 is a top plan view thereof;

FIG. 5 is a front elevation view thereof; and,

FIG. 6 is a bottom plan view thereof.

The ornamental design for a heating device, as shown and described.